In many applications it is necessary to determine the position, velocity, and orientation (“pose” or “state”) in real-time of an aerial vehicle, such as an aircraft, particularly an autonomous aircraft. Global Navigation Satellite System (GNSS) coordinates (e.g., GPS coordinates in the U.S.) are often used in this process. However, sometimes GNSS signals can be lost (i.e., not received or jammed) or there can be errors in the received GNSS coordinates (including through spoofing).